core-agent-linux/network/vif-route-qubes

#!/bin/bash
#============================================================================
# /etc/xen/vif-route-qubes
#
# Script for configuring a vif in routed mode.
# The hotplugging system will call this script if it is specified either in
# the device configuration given to Xend, or the default Xend configuration
# in /etc/xen/xend-config.sxp.  If the script is specified in neither of those
# places, then vif-bridge is the default.
#
# Usage:
# vif-route (add|remove|online|offline)
#
# Environment vars:
# vif         vif interface name (required).
# XENBUS_PATH path to this device's details in the XenStore (required).
#
# Read from the store:
# ip      list of IP networks for the vif, space-separated (default given in
#         this script).
#============================================================================

dir=$(dirname "$0")
# shellcheck disable=SC1091,SC1090
. "$dir/vif-common.sh"

#main_ip=$(dom0_ip)
lockfile=/var/run/xen-hotplug/vif-lock

# shellcheck disable=SC2154
if [ "${ip}" ]; then
    # IPs as seen by this VM
    netvm_ip="$ip"
    netvm_gw_ip=$(qubesdb-read /qubes-netvm-gateway)
    netvm_dns1_ip=$(qubesdb-read /qubes-netvm-primary-dns)
    netvm_dns2_ip=$(qubesdb-read /qubes-netvm-secondary-dns)

    back_ip="$netvm_gw_ip"

    # IPs as seen by the VM - if other than $netvm_ip
    appvm_gw_ip="$(qubesdb-read "/mapped-ip/$ip/visible-gateway" 2>/dev/null || :)"
    appvm_ip="$(qubesdb-read "/mapped-ip/$ip/visible-ip" 2>/dev/null || :)"
fi

# Apply NAT if IP visible from the VM is different than the "real" one
# See vif-qubes-nat.sh for details
if [ -n "$appvm_ip" ] && [ -n "$appvm_gw_ip" ] && [ "$appvm_ip" != "$netvm_ip" ]; then
    # shellcheck disable=SC2154
    if test "$command" == online; then
        # shellcheck disable=SC2154
        echo 1 >"/proc/sys/net/ipv4/conf/${vif}/proxy_arp"
    fi

    # shellcheck source=network/vif-qubes-nat.sh
    . "$dir/vif-qubes-nat.sh"
fi

# shellcheck disable=SC2154
case "$command" in
	online)
		ifconfig "${vif}" up
		echo 1 >"/proc/sys/net/ipv4/conf/${vif}/proxy_arp"
		ipcmd='add'
		iptables_cmd='-I PREROUTING 1'
		cmdprefix=''
		;;
	offline)
		do_without_error ifdown "${vif}"
		ipcmd='del'
		iptables_cmd='-D PREROUTING'
		cmdprefix='do_without_error'
		;;
esac

domid=${vif/vif/}
domid=${domid/.*/}
# metric must be possitive, but prefer later interface
#  32752 is max XID aka domid
metric=$(( 32752 - domid ))

if [ "${ip}" ] ; then
	# If we've been given a list of IP addresses, then add routes from dom0 to
	# the guest using those addresses.
	for addr in ${ip} ; do
		${cmdprefix} ip route "${ipcmd}" "${addr}" dev "${vif}" metric "$metric"
	done
	echo -e "*raw\n$iptables_cmd -i ${vif} ! -s ${ip} -j DROP\nCOMMIT" | \
		${cmdprefix} flock $lockfile iptables-restore --noflush
	${cmdprefix} ip addr "${ipcmd}" "${back_ip}/32" dev "${vif}"
fi

log debug "Successful vif-route-qubes $command for $vif."
if [ "$command" = "online" ]
then
  # disable tx checksumming offload, apparently it doesn't work with our ancient qemu in stubdom
  do_without_error ethtool -K "$vif" tx off
  success
fi